Identifying a Most Suitable Growing Medium for Acclimatizing Dendrobium Orchids for Commercial Purposes

Abstract

Dendrobium orchid highly valued as cut flowers. During acclimatization different growing media are being used. However, these media have not scientifically tested, thus, the effect of growing media on acclimatization stage of Dendrobium orchid type ‘TC 05’ was evaluated under glass house conditions to assist in producing quality pot plants. The experiment was carried out at the Orchid Section of the Floriculture Research and Development Unit (FRDU), Department of National Botanic Gardens (DNBG), Peradeniya, Sri Lanka. Six months old tissue cultured Dendrobium plants with an average mean height of 2.4 cm were potted in 12.7 cm clay pots and five different potting media were tested. Fifteen pots were used for each treatment with 05 plants in each pot (total number of plants in each treatment = pots 15 x 5 plants = 75 plants) with the total number of plants 5 x 15 x 5 = 375 plants. Five different potting media were (T1) Coir dust+ Roof tile pieces + Sand (1:1:1), (T2) Coir dust + Granite + Sand (1:1:1), (T3) Coir dust + Roof tile pieces + Charcoal (1:1:1), (T4) Coir dust + Roof tile pieces + Granite (1:1:1), and (T5) Coir dust + Charcoal + Paddy husk (1:1:1) were used in the experiment. The experiment was arranged according to the Randomized Complete Block Design. The T1 medium Coir dust+ Roof tile pieces + Sand (1:1:1), which is regularly used as the growing media of the FRDU of the DNBG, was considered to be the control treatment. Observation on growth parameters (height, number of new leaves and number of new tillers) of plants were recorded twice a month from October 2022 to June 2023. Mean height of plants in treatment two is (6.4 ± 0.58) significantly higher than those of T3, T4 and T5 (F=5.7, P<0.01). Similarly mean number of new leaves in treatment two (5.2 ± 0.69) is significantly higher than those of T3, T4 and T5 (F=25.72, P<0.01). However, mean number of tiller in treatment two (1.9 ± 0.35) is significantly higher than that of T5 ( F=4.3, P<0.01). Thus growing media (T2) Coir dust + Granite + Sand (1:1:1) showed the best performance in average plant height, number of leaves produced and number of tillers. It may be concluded that Coir dust + Granite + Sand (1:1:1) is the most suitable media for the acclimatization stage (6 to 14 months plants after tissue culture) of Dendrobium verity ‘TC 05’ under local climatic condition in a glass house with 70% shade.